packagegroup-self-hosted: move graphics packages to graphics group

packagegroup-self-hosted: move graphics packages to graphics group

The following packages are gui based tools:
  xdg-utils       # A set of common interfaces for desktop
  leafpad         # A GTK+ text editor used in Build Appliance
  midori          # A web browser used in Build Appliance
  pcmanfm         # PCManFm file manager used in Build Appliance
  vte             # Virtual terminal emulator GTK+ widget library

Move them to packagegroup-self-hosted-graphics so that we can make
a graphics free self-hosted image by excluding the
packagegroup-self-hosted-graphics.

(From OE-Core rev: bb7d081ccb5a352d3089b6b30ab740e62c05e791)

Signed-off-by: Jackie Huang <jackie.huang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>